A resonator operating with bulk acoustic waves, also referred to as a thin-film resonator or FBAR (FBAR=thin-film BAW resonator) has a piezoelectric layer that is arranged between two electrode layers. Thin-film resonators of the diaphragm type that are arranged over a cavity formed in a carrier substrate are known from the publication U.S. Pat. No. 6,262,637 B1. Furthermore, thin-film resonators that are arranged on an acoustic mirror are known, for example, from the publications WO 01/06646, US 2004/0140869 and DE 10241425 A1. Layers are deposited in succession on a substrate and are structured into resonators which are interconnected electrically, and together realize a filter circuit, for example.
In case a filter comprising a thin-film resonator heats up, its characteristic curve migrates in certain situations to lower frequencies. The insertion loss at the right edge of the passband also increases, which results in an even greater heating of the resonators in this frequency range. When the limit of the power compatibility is exceeded, the acoustic component is destroyed.